We have studied the effects of
urapidil 0.4 mg kg-1 i.v. and
clonidine 2.5 micrograms kg-1 i.v. on left ventricular volume and function in 20 patients with chronic
coronary artery disease and
essential hypertension. Patients were studied using 99mtechnetium
radionuclide angiography with first-pass and ECG-gated equilibrium blood-pool techniques and non-invasive sphygmomanometry. Administration of both
urapidil and
clonidine caused a similar decrease in mean arterial pressure (20%), associated with an equivalent reduction in systemic vascular resistance. Despite the decrease in mean arterial pressure, heart rate did not change after administration of
clonidine, but there was an early and transient increase of 13% after
urapidil. There were no changes in cardiac index, but in contrast with
clonidine,
urapidil caused a decrease in
stroke index. In both groups, global left ventricular ejection fraction did not change.
Urapidil produced a mean decrease in end-diastolic volume of 8% and a mean decrease in end-systolic volume of 13%, in contrast with
clonidine which caused little change. Reduced arterial pressure, systemic vascular resistance and preload after
urapidil 0.4 mg kg-1 i.v., associated with lack of prolonged
tachycardia and preserved global left ventricular performance, may have obvious clinical implications in anaesthesia.